/*
 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS HEADER.
 *
 * Copyright 1997-2007 Sun Microsystems, Inc.  Portions Copyrighted 2008 Richard Schilling.
 *
 * The contents of this file are subject to the terms of either the GNU
 * General Public License Version 2 only ("GPL") or the Common Development
 * and Distribution License("CDDL") (collectively, the "License").  You
 * may not use this file except in compliance with the License. You can obtain
 * a copy of the License at https://glassfish.dev.java.net/public/CDDL+GPL.html
 * or glassfish/bootstrap/legal/LICENSE.txt.  See the License for the specific
 * language governing permissions and limitations under the License.
 *
 * When distributing the software, include this License Header Notice in each
 * file and include the License file at glassfish/bootstrap/legal/LICENSE.txt.
 * Sun designates this particular file as subject to the "Classpath" exception
 * as provided by Sun in the GPL Version 2 section of the License file that
 * accompanied this code.  If applicable, add the following below the License
 * Header, with the fields enclosed by brackets [] replaced by your own
 * identifying information: "Portions Copyrighted [year]
 * [name of copyright owner]"
 *
 * Contributor(s): Richard Schilling (coderroadie@gmail.com)
 *
 * If you wish your version of this file to be governed by only the CDDL or
 * only the GPL Version 2, indicate your decision by adding "[Contributor]
 * elects to include this software in this distribution under the [CDDL or GPL
 * Version 2] license."  If you don't indicate a single choice of license, a
 * recipient has the option to distribute your version of this file under
 * either the CDDL, the GPL Version 2 or to extend the choice of license to
 * its licensees as provided above.  However, if you add GPL Version 2 code
 * and therefore, elected the GPL Version 2 license, then the option applies
 * only if the new code is made subject to such option by the copyright
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 */

package com.sun.mail.util;

import java.io.*;

/**
 * This class implements a BASE64 encoder. It is implemented as
 * a FilterOutputStream, so one can just wrap this class around
 * any output stream and write bytes into this filter. The encoding
 * is done as the bytes are written out.
 * 
 * @author John Mani
 * @author Bill Shannon
 */

public class BASE64EncoderStream extends FilterOutputStream {

    private byte[] buffer; 	// cache of bytes that are yet to be encoded
    private int bufsize = 0;	// size of the cache
    private byte[] outbuf; 	// line size output buffer
    private int count = 0; 	// number of bytes that have been output
    private int bytesPerLine;	// number of bytes per line
    private int lineLimit;	// number of input bytes to output bytesPerLine
    private boolean noCRLF = false;

    private static byte[] newline = new byte[] { '\r', '\n' };

    /**
     * Create a BASE64 encoder that encodes the specified output stream.
     * 
     * @param out the output stream
     * @param bytesPerLine number of bytes per line. The encoder inserts
     *            a CRLF sequence after the specified number of bytes,
     *            unless bytesPerLine is Integer.MAX_VALUE, in which
     *            case no CRLF is inserted. bytesPerLine is rounded
     *            down to a multiple of 4.
     */
    public BASE64EncoderStream(OutputStream out, int bytesPerLine) {
        super(out);
        buffer = new byte[3];
        if (bytesPerLine == Integer.MAX_VALUE || bytesPerLine < 4) {
            noCRLF = true;
            bytesPerLine = 76;
        }
        bytesPerLine = (bytesPerLine / 4) * 4;	// Rounded down to 4n
        this.bytesPerLine = bytesPerLine;	// save it
        lineLimit = bytesPerLine / 4 * 3;

        if (noCRLF) {
            outbuf = new byte[bytesPerLine];
        } else {
            outbuf = new byte[bytesPerLine + 2];
            outbuf[bytesPerLine] = (byte) '\r';
            outbuf[bytesPerLine + 1] = (byte) '\n';
        }
    }

    /**
     * Create a BASE64 encoder that encodes the specified input stream.
     * Inserts the CRLF sequence after outputting 76 bytes.
     * 
     * @param out the output stream
     */
    public BASE64EncoderStream(OutputStream out) {
        this(out, 76);
    }

    /**
     * Encodes <code>len</code> bytes from the specified <code>byte</code> array
     * starting at offset <code>off</code> to
     * this output stream.
     * 
     * @param b the data.
     * @param off the start offset in the data.
     * @param len the number of bytes to write.
     * @exception IOException if an I/O error occurs.
     */
    public synchronized void write(byte[] b, int off, int len) throws IOException {
        int end = off + len;

        // finish off incomplete coding unit
        while (bufsize != 0 && off < end)
            write(b[off++]);

        // finish off line
        int blen = ((bytesPerLine - count) / 4) * 3;
        if (off + blen < end) {
            // number of bytes that will be produced in outbuf
            int outlen = encodedSize(blen);
            if (!noCRLF) {
                outbuf[outlen++] = (byte) '\r';
                outbuf[outlen++] = (byte) '\n';
            }
            out.write(encode(b, off, blen, outbuf), 0, outlen);
            off += blen;
            count = 0;
        }

        // do bulk encoding a line at a time.
        for (; off + lineLimit <= end; off += lineLimit)
            out.write(encode(b, off, lineLimit, outbuf));

        // handle remaining partial line
        if (off + 3 < end) {
            blen = end - off;
            blen = (blen / 3) * 3;	// round down
            // number of bytes that will be produced in outbuf
            int outlen = encodedSize(blen);
            out.write(encode(b, off, blen, outbuf), 0, outlen);
            off += blen;
            count += outlen;
        }

        // start next coding unit
        for (; off < end; off++)
            write(b[off]);
    }

    /**
     * Encodes <code>b.length</code> bytes to this output stream.
     * 
     * @param b the data to be written.
     * @exception IOException if an I/O error occurs.
     */
    public void write(byte[] b) throws IOException {
        write(b, 0, b.length);
    }

    /**
     * Encodes the specified <code>byte</code> to this output stream.
     * 
     * @param c the <code>byte</code>.
     * @exception IOException if an I/O error occurs.
     */
    public synchronized void write(int c) throws IOException {
        buffer[bufsize++] = (byte) c;
        if (bufsize == 3) { // Encoding unit = 3 bytes
            encode();
            bufsize = 0;
        }
    }

    /**
     * Flushes this output stream and forces any buffered output bytes
     * to be encoded out to the stream.
     * 
     * @exception IOException if an I/O error occurs.
     */
    public synchronized void flush() throws IOException {
        if (bufsize > 0) { // If there's unencoded characters in the buffer ..
            encode();      // .. encode them
            bufsize = 0;
        }
        out.flush();
    }

    /**
     * Forces any buffered output bytes to be encoded out to the stream
     * and closes this output stream
     */
    public synchronized void close() throws IOException {
        flush();
        if (count > 0 && !noCRLF) {
            out.write(newline);
            out.flush();
        }
        out.close();
    }

    /** This array maps the characters to their 6 bit values */
    private final static char pem_array[] = { 'A', 'B', 'C', 'D', 'E', 'F', 'G', 'H', // 0
    'I', 'J', 'K', 'L', 'M', 'N', 'O', 'P', // 1
    'Q', 'R', 'S', 'T', 'U', 'V', 'W', 'X', // 2
    'Y', 'Z', 'a', 'b', 'c', 'd', 'e', 'f', // 3
    'g', 'h', 'i', 'j', 'k', 'l', 'm', 'n', // 4
    'o', 'p', 'q', 'r', 's', 't', 'u', 'v', // 5
    'w', 'x', 'y', 'z', '0', '1', '2', '3', // 6
    '4', '5', '6', '7', '8', '9', '+', '/'  // 7
    };

    /**
     * Encode the data stored in <code>buffer</code>.
     * Uses <code>outbuf</code> to store the encoded
     * data before writing.
     * 
     * @exception IOException if an I/O error occurs.
     */
    private void encode() throws IOException {
        int osize = encodedSize(bufsize);
        out.write(encode(buffer, 0, bufsize, outbuf), 0, osize);
        // increment count
        count += osize;
        // If writing out this encoded unit caused overflow,
        // start a new line.
        if (count >= bytesPerLine) {
            if (!noCRLF)
                out.write(newline);
            count = 0;
        }
    }

    /**
     * Base64 encode a byte array. No line breaks are inserted.
     * This method is suitable for short strings, such as those
     * in the IMAP AUTHENTICATE protocol, but not to encode the
     * entire content of a MIME part.
     */
    public static byte[] encode(byte[] inbuf) {
        if (inbuf.length == 0)
            return inbuf;
        return encode(inbuf, 0, inbuf.length, null);
    }

    /**
     * Internal use only version of encode. Allow specifying which
     * part of the input buffer to encode. If outbuf is non-null,
     * it's used as is. Otherwise, a new output buffer is allocated.
     */
    private static byte[] encode(byte[] inbuf, int off, int size, byte[] outbuf) {
        if (outbuf == null)
            outbuf = new byte[encodedSize(size)];
        int inpos, outpos;
        int val;
        for (inpos = off, outpos = 0; size >= 3; size -= 3, outpos += 4) {
            val = inbuf[inpos++] & 0xff;
            val <<= 8;
            val |= inbuf[inpos++] & 0xff;
            val <<= 8;
            val |= inbuf[inpos++] & 0xff;
            outbuf[outpos + 3] = (byte) pem_array[val & 0x3f];
            val >>= 6;
            outbuf[outpos + 2] = (byte) pem_array[val & 0x3f];
            val >>= 6;
            outbuf[outpos + 1] = (byte) pem_array[val & 0x3f];
            val >>= 6;
            outbuf[outpos + 0] = (byte) pem_array[val & 0x3f];
        }
        // done with groups of three, finish up any odd bytes left
        if (size == 1) {
            val = inbuf[inpos++] & 0xff;
            val <<= 4;
            outbuf[outpos + 3] = (byte) '=';	// pad character;
            outbuf[outpos + 2] = (byte) '=';	// pad character;
            outbuf[outpos + 1] = (byte) pem_array[val & 0x3f];
            val >>= 6;
            outbuf[outpos + 0] = (byte) pem_array[val & 0x3f];
        } else if (size == 2) {
            val = inbuf[inpos++] & 0xff;
            val <<= 8;
            val |= inbuf[inpos++] & 0xff;
            val <<= 2;
            outbuf[outpos + 3] = (byte) '=';	// pad character;
            outbuf[outpos + 2] = (byte) pem_array[val & 0x3f];
            val >>= 6;
            outbuf[outpos + 1] = (byte) pem_array[val & 0x3f];
            val >>= 6;
            outbuf[outpos + 0] = (byte) pem_array[val & 0x3f];
        }
        return outbuf;
    }

    /**
     * Return the corresponding encoded size for the given number
     * of bytes, not including any CRLF.
     */
    private static int encodedSize(int size) {
        return ((size + 2) / 3) * 4;
    }

    /***
     * begin TEST program
     * public static void main(String argv[]) throws Exception {
     * FileInputStream infile = new FileInputStream(argv[0]);
     * BASE64EncoderStream encoder = new BASE64EncoderStream(System.out);
     * int c;
     * while ((c = infile.read()) != -1)
     * encoder.write(c);
     * encoder.close();
     * }
     *** end TEST program
     **/
}
